1. Field of the Invention
The present invention relates to a connecting structure for a plate material and an opposite member and to a head suspension with the connecting structure incorporated in, for example, a hard disk drive.
2. Description of Related Art
A head suspension incorporated in a hard disk drive has a slider that slightly flies or floats with respect to a hard disk to write/read data to and from the hard disk. For recent hard disk drives, high recording density is required and a flying height of a slider lowers yearly according to the high recording density. Currently, a flying height lowers down to several nanometers. As a flying height lowers, needs for high cleanliness of a head suspension incorporated in a hard disk drive are increasing.
For this, there are techniques for preventing a head suspension as a product from producing particles as disclosed in Japanese Unexamined Patent Application Publications No. 2002-133813 and No. 2002-184139.
In JP 2002-133813 A, a head suspension includes a load beam on which a flexure is laid. The flexure longitudinally extends along the head suspension and has a bend that laterally protrudes from the load beam in the middle of the head suspension. To prevent the bent and the load beam from wearing out each other, the load beam is provided with a curved edge or a chamfered edge.
In JP 2002-184139 A, a head suspension includes piezoelectric elements made of, for example, PZT (lead zirconate titanate). Each piezoelectric element has peripheral side faces coated with resin to prevent particles from dropping off the side faces.
These techniques promise a certain level of effect for preventing a head suspension as a product from producing particles.
On the other hand, a product of each head suspension is cleaned by ultrasonic cleaning in a bath filled with pure water to effectively remove particles as contamination stuck to the product before shipment thereof. In the ultrasonic cleaning, there is a new problem.
As illustrated in FIG. 17, a recent head suspension 101 includes a flexure 103 and a load beam 105 laid on the flexure 103. The flexure 103 and load beam are very thin plates made of metal foils with respective thicknesses of, for example, 18 um and 30 um and are fixed to each other by laser welding. The thin plates of the flexure 103 and load beam 105 cause slight gaps 111, 113 and 115 due to deformation of the thin plates of the metal foils at portions on the load beam 5, around a resilient part and a piezoelectric element between welded points 107 and 109.
In the gaps 111, 113 and 115, the thin plates hit each other by ultrasonic vibration at the time of the cleaning. This slightly breaks a metal surface of each thin plate to generate fine particles.
Although the particles are almost removed through the cleaning, some particles may be retained in the gaps 111, 113 and 115 until the cleaned product is incorporated in a hard disk drive. In this case, the product involves a risk of dropping the particles off the gaps 111, 113 and 115 in the hard disk drive.
Further, the product with the gaps reduces the accuracy of evaluation of cleanliness with use of a liquid particle counter (LPC). Namely, the product produces particles by ultrasonic vibration at the time of extraction of particles as contamination to be originally measured. The produced particles are added to the particles to be originally measured, so that the evaluation of the cleanliness becomes inaccurate.